If your networking equipment is sufficiently aware, this traffic will receive preferential treatment.

You can filter these values pretty easily using the ip.dsfield.dscp display filter — just right-click on the DSCP field in the packet like so:

Applying a DSCP display filter

What if you need to use DSCP in a capture filter?

To match against a particular DSCP codepoint using BPF (WinPcap/libpcap’s filtering language) you need to take the bit pattern, left-shift it two places to account for the ECN, and mask out the ECN. For EF (101110) you’d have do something like this: